With the development of display technology, an OLED (Organic Light Emitting Diode), which is a current-controlled light-emitting device, has being increasingly applied in the field of high-performance display, due to the characteristics such as self-illumination, fast response, wide viewing angle and capability of being fabricated on flexible substrate.
The OLED pixel circuit has a circuit structure for driving the organic light emitting diode to emit light by controlling current using a driving transistor. In order to eliminate the influence of uneven threshold voltage of the driving transistor, typically the circuit structure of the pixel circuit the organic light emitting diode further comprises a module for compensating the threshold voltage. The OLED pixel circuit compensates the OLED pixels through a reset phase, a compensation potential writing phase and a light emitting phase, a driving transistor connected to the OLED is discharged till it is turned off in the compensation potential writing phase, thereby the driving transistor is discharged to a potential Vth (threshold voltage).
However, with the improvement of the resolution, the driving transistor is required to be discharged within a short period, and discharging of the driving transistor has a specific function of time, the driving transistor may be insufficiently discharged with a short discharging time, and a preset display brightness of the OLED may not be achieved.